Effect of volumetric oxygen transfer coefficient (kLa) on ethanol production performance by Scheffersomyces stipitis on hemicellulosic sugarcane bagasse hydrolysate

• A contribution to a technological and energy analysis of ethanol production from SBHH.
• Ethanol production was strongly influenced by the volumetric oxygen transfer coefficient.
• The lower aeration with higher agitation improved xylose bioconversion into ethanol.

Experimental evaluation of the effect of the agitation speed and aeration rate (measured by kLa) and energy required for ethanol production using sugarcane bagasse hemicellulosic hydrolysate (SBHH) by Scheffersomyces stipitis were studied. Fermentation and purification stages were simulated using the software Aspen Plus with experimental data to understand the overall energy performance of the process. In all experiments, fermentative parameters and the thermal energy required in the ethanol production process were strongly influenced by kLa values. The optimum initial kLa to achieve the maximal ethanol concentration (15.03 g L−1) and the minimal thermal energy required (1.85 × 105 KW per kg ethanol), were found at 8.0 h−1 (450 rpm and 0.6 vvm). Under this condition, the ethanol yield and productivity were 0.37 g g−1 and 0.30 g L−1 h−1, respectively. The current study highlights the ethanol production improvement from hemicellulose hydrolysate by S. stipitis and will contribute to developing a more efficient strategies for fermentation of both cellulose and hemicellulose hydrolysates.